A basic function of the air conditioning system of a plane is to adjust air from the ambience, which has been processed by an air-conditioning assembly, into desired air-conditioned air with appropriate temperature and humidity. This air-conditioned air is distributed inside a cabin through an air-conditioning pipeline.
Commercial aircrafts generally have a wide operation range and a special use environment. Its external environment changes greatly. Therefore, in some areas or hot working conditions of some areas, the humidity of ambient air will be very high. The external air with a relatively high humidity, after being subject to cooling processing by a refrigeration assembly of the air conditioning system of the airplane, the air temperature will drop while the relative humidity rises. When the relative humidity of the air reaches 100%, liquid water will exist in the air. Further, when the liquid water in the air-conditioned air reaches a certain concentration, it will enter into a cabin along the air-conditioning distribution pipeline, thereby forming “rain within cabin.”
For example, In Sanya, Hainan where the temperature and humidity are usually very high, the moisture content of the air in July amounts to 19 k/kg dry air, which corresponds to a dew-point temperature of 23.5° C. That is, when an absolute humidity of the ambient air is constant and the temperature drops to 23.5° C., liquid water will be precipitated from the air. This is liquid water in the air.
On the other hand, when the humidity within the cabin is relatively high, the humidity of recycled air will also be high; while the relatively high temperature of the recycled air causes moisture in the recycled air to exist in a gas state before the moisture in the recycled air enters into a mixing cavity. After the recycled air enters into the mixing cavity, it is mixed with fresh air-conditioned air from the air conditioning assembly, and the temperature will drop rapidly. When the temperature is lower than the dew point temperature of the mixed air, moisture in the mixed air will be transformed into a liquid state from a gas state.
Further, when the air temperature is below 0° C., the liquid-state water in the air will form ice particles; as a result, ice-block will occur to a downstream condenser of refrigeration assembly of the air-conditioner system.
In order to effectively prevent occurrence of the ice-block phenomenon, current three-wheel-type refrigeration assembly cannot drop the air temperature too lowly at an outlet of the air-conditioning assembly. Although the three-wheel-type refrigeration assembly dewaters by high pressure such that the dewatering efficiency has been enhanced somewhat compared with earlier air conditioning assemblies, the three-wheel-type refrigeration assembly cannot remove completely the moisture in the air-conditioned air due to influence of ice-block on three-wheel-type refrigeration assembly. Therefore, under a working condition of a higher ambient air humidity (e.g., hot ground), liquid-state water or even ice will always exist in the air-conditioned air of the air-conditioning assembly. Currently, the dewatering efficiency of a newer model full-electricity air-conditioning assembly is also limited by air pressure conditions and the efficiency of the dewatering device such that it cannot effectively remove moisture in the air in the air-conditioning assembly.
Such liquid-state water or ice which fails to be removed timely will always enter into the cabin along an air-conditioning pipeline, and the crews and passengers will feel the water dropping phenomenon within the cabin, thereby reducing the comfort degree in the cabin.
FIG. 1 illustrates a schematic diagram of a dewatering mechanism of a three-wheeled air-conditioning system in the prior art. As illustrated in FIG. 1, a water separating device is additionally mounted between a condenser and a regenerator of the air-conditioning assembly. The water separating device increases a momentum of water drops in a mechanical way to remove free water drops in the air. However, due to limitation of air temperature, not all moisture in the air is precipitated into free water drops. Extra moisture in the air will further form free water drops after the air passes through a turbine, while this part of free water drops formed through the turbine will usually enters into the cabin along with the air, which dampens the comfort of crews and passengers in the cabin; meanwhile, it will also cause corrosion of a fuselage structure or increase a fault rate of electrical appliances within the cabin.
FIG. 2 illustrates a schematic diagram of a dewatering mechanism of a four-wheel type air conditioning system in the prior art. Similar to FIG. 1, in the four-wheel type air conditioning system in FIG. 2, a water separating device is also additionally mounted between the condenser and the regenerator of the air conditioning assembly to remove free water drops in the air. However, although the dewatering efficiency of the four-wheel type air conditioning system is slightly higher than a three-wheel type air conditioning system, it cannot remove liquid-state water regenerated within the mixing cavity.
Therefore, the air-conditioning system above cannot effectively control liquid-state water content in the air entering into the cabin.